Proposed Polynomial Model Research Articles

Parameter optimization, characterization, and crystallization mechanisms underlying the synthesis of zeolite A using liquid crystal display waste glass and sandblasting waste as alternative raw materials

This paper examines the synthesis of zeolite A via hydrothermal alkali fusion using liquid crystal display waste glass (LCDWG) and sandblasting waste (SB). The design of the experiments was determined using the Box-Behnken method in conjunction with response surface design. Three factors were shown to have a pronounced effect on synthesis outcomes: (i) Si/Al molar ratio, (ii) crystallization temperature, and (iii) crystallization period. Synthesis parameters were optimized in accordance with the crystallinity (%) of the zeolite. XRD results revealed that increasing the Si/Al ratio improved the crystallinity and phase purity of the synthesized zeolite A. Increasing the crystallization temperature altered the crystal type and enhanced crystal purity; however, excessive temperatures reduced crystallinity and led to decomposition of the zeolite A phase. SEM results revealed that the resulting zeolite A possessed a cubic structure. ANOVA revealed that the Si/Al molar ratio had the most profound effect on the synthesis of zeolite A, followed by crystallization duration and crystallization temperature. The fact that the R2 value (0.95) was similar to the adjusted R2 value (0.8736) confirmed the efficacy of the proposed polynomial model. A highly significant F-value of 11.75 confirmed that the proposed model could be used for design purposes. The excellent water adsorption/desorption performance of the proposed zeolite A (49.83 g/ m2; meeting JIS A 1470 standards) indicates its suitability as a low-cost construction material for a variety of applications. The ultimate objective of this study was to overcome difficulties encountered in the disposal of industrial waste by converting LCDWG and SB into zeolite A.

Machine learning-based modeling of the coupling effect of strain rate and temperature on strain hardening for 5182-O aluminum alloy

This research characterizes the dynamic hardening behavior of an aluminum alloy sheet of 5182-O for the coupling effect of strain rate and temperature. Tests are carried out for dogbone specimens at different loading conditions to experimentally characterize the strain rate hardening and thermal softening effect for the alloy. The behaviours are then modeled by the Johnson-Cook, Zerilli-Armstrong and Lim-Huh models. In addition, the FEA-friendly polynomial model and artificial neural network (ANN) model are used to describe the highly non-linearity and coupling of strain hardening. Factors affecting ANN predicting accuracy and numerical computing efficiency are comprehensively studied including network structure, parameter settings and optimization algorithms. All the analytical and ANN models are also implemented into ABAQUS/Explicit to numerically compute the reaction force of tensile tests of dogbone specimens. The strain hardening curves are predicted by the analytical and ANN models for the comparison with experimental measurements to evaluate their performance. The experimental results show that the strain rate is slightly negative at room temperature, while the strain rate effect turns to be positive as temperature rises. The comparison of the flow curves between prediction and experiments reveals that the coupling effect is reasonably illustrated by the proposed polynomial model and the ANN model illustrates the flow curves with the dramatically much better accuracy than all the other models. The numerically predicted reaction forces prove that the ANN model accurately illustrates the load capability with the best agreement among the models studied in this research. The numerical computation also shows that the numerical computation efficiency of the ANN model is slightly reduced compared with analytical models, but the reduction is not much and worthwhile compared with the high accuracy of ANN.

Fast Maximum Torque per Ampere (MTPA) Angle Detection for Interior PMSMs using Online Polynomial Curve Fitting

For interior permanent magnet synchronous machines (IPMSMs), maximum torque per ampere (MTPA) control aims to find the MTPA angle to maximize the control objective (the ratio of output torque to stator current). This article proposes a novel online polynomial curve fitting technique for fast and accurate MTPA angle detection, which is motivated by the fact that the objective increases before MTPA angle and decreases after MTPA angle. This article proposes a polynomial-based objective model and identifies the polynomial parameters from a few test data for direct MTPA angle calculation. The proposed approach can avoid the time-consuming search process resulting in fast detection speed in comparison to existing search-based methods. In implementation, the current angle is set to a few test values to obtain the data for online curve fitting and MTPA angle calculation, in which there is no need of machine inductances and PM flux linkage. Moreover, the proposed polynomial model is analyzed to obtain the number of test data required for fast and accurate MTPA angle detection. The proposed approach is validated with extensive experiments and comparisons with existing methods on a laboratory IPMSM.

A Fuzzy Model for Noise Estimation in Magnetic Resonance Images

Background and objectivesNoise is a critical factor which destroys the visual clarity of Magnetic Resonance (MR) images. In many of the denoising schemes used on MR images, the depth of denoising is decided based on the strength of noise and their operational parameters are tuned in proportion to the Standard Deviation (SD) of noise. Most of the state-of-the-art noise models estimate noise statistics indirectly from the standard probability density function of choice, fitted on the image histogram. A mathematical model to estimate the noise statistics in Magnetic Resonance (MR) images, from the image fuzziness is proposed in this work. Material and methodsNoise significantly affects the randomness of gray levels, gradient and fuzziness of the image. Based on this principle, a direct method for computing the noise variance is proposed in this paper. Noise variance of the image is directly estimated from the fuzziness of the noisy image by using the polynomial model. The fuzzy membership values at each pixel are set in proportion to the normalized local gradient. ResultsOn phantom studies, quadratic index of fuzziness is observed to be well-correlated with standard deviation of noise with a correlation of 0.9532±0.3315. The proposed polynomial model exhibited a goodness of fit, r = 0.9996. The model is found to be superior to the existing models with regard to Root Mean Squared Error (RMSE). ConclusionOn simulation studies on MR phantom, noise variance is found to be well-correlated with image fuzziness. The proposed model exhibited high goodness of fit. The model is found to be superior to the noise models available in literature in terms of Root Mean Square Error (RMSE). The principle of the proposed fuzziness based noise model is straightforward compared to indirect noise models which make use of image histogram.

Modelling of plant species richness along altitudinal gradient: Asalem Watershed basin, temperate deciduous forests in northern Iran

Among the various topographical factors, effects of altitudinal factor on species diversity, richness, composition and biological functions patterns are considerable. This study was done to investigate plant species richness along altitudinal gradient in the Asalem watershed basin, northern forests of Iran. For these purpose, 13 altitudinal transects were established from 100 to 2500 m, according to altitude ranges within 200 m intervals. Data collection was done in 216 circular plots of 1000-m2 area with a distance of 150 m from each other. In total, 576species of 325 genus and 96 families were recorded. The highest number of species was belonged to Asteracese، Fabaceae and Lamiaceae families. The results indicated that forbs with 414 species belong to54 families and ferns with 31 species belong to10 families were the largest and smallest group of plants in study area respectively. In herbaceous layer, the mean number of species was increased along altitudinal gradients (P ≤ 0.005). The lowest and highest value of species number was belonged to 500 and 2500 m altitudes, respectively. Generally, there was a gradual decline of species number at 100 to 500 m. Fitted models indicated that variation patterns at altitudinal gradients were significant and the proposed polynomial model had a high conformity with changes of species richness. The lowest value of species number in woody layer was belonged to 1900 m altitude and 2100 m had the highest value. Three peak points were recorded at the beginning, middle and the end of gradient, respectively. Sinusoidal models showed a correlation between species richness and altitudinal changes by high coefficient of determination. Results of β –diversity indicated that species change rate was fixed at 700 m altitude, but it was decreased by increasing altitude. Fluctuations of β diversity were followed of the sinusoidal models. In the study area, destructive factors including road construction, tourism and over-exploitation are a serious threat for the ecosystem and this study can be considerable to develop targeted strategies for conservation of plant diversity. In addition, study of habitat conditions in each altitudinal gradients is necessary to reconstruction stands with low species diversity and appropriate species selection to establish stands with high density.

Dynamic increase factor for progressive collapse analysis of semi-rigid steel frames

An empirical and efficient method is presented for calculating the dynamic increase factor to amplify the applied loads on the affected bays of a steel frame structure with semi-rigid connections. The nonlinear static alternate path analysis is used to evaluate the dynamic responses. First, the polynomial models of the extended end plate and the top and seat connection are modified, and the proposed polynomial model of the flush end plate connection shows good agreement as compared with experimental results. Next, a beam model with nonlinear spring elements and plastic hinges is utilized to incorporate the combined effect of connection flexibility and material nonlinearity. A new step-by-step analysis procedure is established to obtain quickly the dynamic increase factor based on a combination of the pushdown analysis and nonlinear dynamic analysis. Finally, the modified dynamic increase factor equation, defined as a function of the maximum ratio value of energy demand to energy capacity of an affected beam, is derived by curve fitting data points generated by the different analysis cases with different column removal scenarios and five types of semi-rigid connections.

Evaluation and development of temperature-based empirical models for estimating daily global solar radiation in humid regions

In the present study, 14 existing temperature–based empirical models for daily horizontal global solar radiation estimation were comprehensively reviewed, and six new temperature–based models (P1P6) were developed for solar radiation estimation in humid regions. The accuracy and suitability of these models were further evaluated for the humid subtropical and tropical regions of China as a case study using meteorological data during 1966–2015 from 20 radiation stations. The results indicated that despite most studied models were capable of estimating daily global solar radiation with reasonable accuracy, the accuracy of the single temperature-based models was much improved when daily precipitation and relative humidity were included in the models. The newly proposed polynomial model P2 was the top-ranked single temperature-based model for most radiation stations and thus recommended at sites where only air temperatures were available. In terms of complex temperature-based models, the proposed models P3 and P5 by incorporating a proposed logarithmic form of precipitation and the actual value of relative humidity were superior to the existing complex models. Generally, the proposed temperature–based models can be applied for daily global solar radiation estimation with higher accuracy in humid subtropical and tropical regions of China and maybe elsewhere with similar climates.

A polynomial model for the adaptive computation of threshold of gradient modulus in 2D anisotropic diffusion filter

Anisotropic Diffusion (AD) filter is a non-linear spatial filter, widely used for denoising Magnetic Resonance (MR) images. But, the degree of smoothening and the quality of the morphological edges in the restored image are greatly influenced by the selection of the optimum value Threshold of Gradient Modulus (TGM), which is one of the important operational parameters of AD filter. The method for tuning TGM to its optimum value through trial and error is subjective, cumbersome and time consuming. As a solution to this, a polynomial model to compute the optimum value of TGM from the Standard Deviation (SD) of the noise is proposed in this article. The optimum values of TGM for MR images with completely different information content and noise statistics have been identified objectively with the help of a novel edge preservation metric termed as ‘Edge Content Ratio (ECR), with the support of subjective assessment of the quality of the restored images. The coefficient of prediction, r2 equal to 0.7431 is observed for the proposed polynomial model, formulated between the values of optimum TGM and SD of the noise, computed from the test MR images.

Polymeric complexes obtained from the interaction of bovine serum albumin and κ-carrageenan

This study aimed to characterize and optimize the formation of polymeric complexes obtained from the interaction between bovine serum albumin (BSA) and κ-carrageenan, in different aqueous systems containing different pH values and various concentrations of polymer and NaCl. Response surface methodology was applied to optimize the process. The proposed polynomial model showed significant adjustment (R2 = 0.84), and the optimal conditions for the formation of carrageenan-BSA polymeric complexes were verified to be 6.40 mg of κ-carrageenan, 0.58 mol/L NaCl, and pH 6.30. The rheological analysis showed that the polymeric complex had a less viscous character than carrageenan. Scanning electron microscopy and X-ray diffractometry showed that the complex had a more well-differentiated morphology compared to the original biopolymers.

Simulation on Force Tracking Control of a Magnetorheological Damper under Impact Loading

This paper focuses on the design of the control structure which consists of inner loop controller employed for MR damper under impact loading by using computer simulation. The simulation is done by using MATLAB 7.0. The structure of the inner loop control for the proposed MR damper model uses a simple PI control to achieve the desired force. In this simulation, the MR damper model that has been validated with the experimental result is used to simulate the actual force that produced by MR damper. The performance of inner loop controller to track the actual force produced by MR damper by obtaining the several input functions which are half wave of sinusoidal, saw-tooth, square and random functions of desired force with the variation in pendulum mass of 15 kg and 20 kg are investigated. It can be seen clearly that under several input functions, the proposed polynomial model with PI controller has the good ability to track the desired damping force under impact loading.

A modifying algorithm of the topological VLSI layer by dummy filling features based on modeling the chemical-mechanical planarization

The approach to modeling chemical-mechanical planarization (CMP) based on the notion of the effective filling density, which makes it possible to calculate the thickness distribution of the interlayer dielectric (ILD) on the surface of the VLSI crystal, is considered. The polynomial CMP model previously proposed in [1] is compared to model [2]. The algorithm of modifying the pattern of the VLSI topological layer by the dummy filling features, which was proposed in [3], is described using the proposed polynomial model. The results of model investigations of applying the developed modification algorithm of topological layers by examples of various VLSI types are presented.

A polynomial analytical model of rubber bearings based on series of tests

Rubber bearings are among the most frequently applied devices in seismic isolation. Although the behavior of rubber bearings under strong earthquakes is nonlinear, it is often interpreted through the bilinear constitutive law. The investigations presented in this paper represent a successful attempt to simulate nonlinear force–displacement relationships. The first part of the paper covers production and testing of rubber bearings and results obtained. The second part deals with development of a simple nonlinear mathematical model of a rubber bearing involving a polynomial function and eight additional parameters obtained from biaxial tests. The polynomial model can simulate the behavior of natural rubber bearings in case of small and large deformations. The model is capable of covering the strengthening of the rubber in conditions of large deformations, including the loading history effect. Based on comparison between the analytical and experimental results, it is concluded that the proposed polynomial model is capable enough to simulate the force–displacement relationship of rubber bearings.

Modeling of wideband radio frequency power amplifiers using Zernike polynomials

In this article, we suggest a new set of basis functions that are based on Zernike polynomials for the behavioral modeling of radio frequency power amplifiers (PAs). The modeling of highly nonlinear PAs exhibits numerical instability that degrades the accuracy of the model parameters and predistorter modeling efficiency. Simulation results show that the proposed polynomial model is more suitable to resolve the numerical instability problem and proves to have greater accuracy with reduced complexity. A Doherty PA driven by a multicarrier wideband code division multiple access signal was used for validation; and, the obtained results show that the new model exhibits superior numerical stability as the nonlinearity order and memory depth of the model increase. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2012. © 2012 Wiley Periodicals, Inc.

Simulation and experimental studies on the behaviour of a magnetorheological damper under impact loading

This paper is aimed to model behaviour of a magnetorheological (MR) damper under impact loading through polynomial approach. The polynomial model is developed based on curve fitting from experimental results and consists of a three regions namely fluid locking, positive and negative acceleration regions. The experimental results which have been performed using impact test apparatus are evaluated in the form of transmitted force in velocity, displacement, and time domain. The simulation results of the proposed polynomial model are then compared with the experimental results. Results show that the proposed polynomial model closely follow the experimental data in the three regions under study namely fluid locking, positive and negative accelerations.

Modelling, characterisation and force tracking control of a magnetorheological damper under harmonic excitation

The objective of this paper is to study the performance of a sixth order polynomial approach to model hysteresis behaviour of a magnetorheological (MR) damper under harmonic excitations. The polynomial model is developed based on curve fitting from the experimental results and consists of a pair subsystem namely positive and negative acceleration which correspond to the upper and lower curves. The performance of the proposed polynomial model is compared with a well known non-parametric technique namely inverse model. The energy dissipated and equivalent damping coefficient of the MR damper in terms of input current and displacement amplitude are investigated. From the simulation results, the sixth order polynomial model shows better performance in describing non-linear hysteresis behaviour of the MR damper compared with inverse model. The force tracking control in both simulation and experimental studies demonstrate that a close-loop PI control has the ability to track the desired damping force well.

Transformation Between Power-law and Polynomial Thin-Film Transistor Models

A procedure is proposed to convert back and forth between two equations used to model the saturation current of thin film transistors. To demonstrate and determine the effectiveness of the proposed procedure, experimental data modeled by the traditional monomial (power-law) model is transformed into a recently proposed polynomial model. Conversely, another set of data, which was originally represented by the polynomial model, is transformed to the monomial model. This procedure is also applied to short-channel crystalline MOSFETs.

Vacuum drying characteristics of eggplants

The vacuum drying characteristics of eggplant were investigated. Drying experiments were carried out at vacuum chamber pressures of 2.5, 5 and 10 kPa, and drying temperature ranging from 30 to 50 °C. The effects of drying pressure and temperature on the drying rate and drying shrinkage of the eggplant samples were evaluated. The suitable model for describing the vacuum drying process was chosen by fitting four commonly used drying models and a suggested polynomial model to the experimental data; the effective moisture diffusivity and activation energy were calculated using an infinite series solution of Fick’s diffusion equation. The results showed that increasing drying temperature accelerated the vacuum drying process, while drying chamber pressure did not show significant effect on the drying process within the temperature range investigated. Drying shrinkage of the samples was observed to be independent of drying temperature, but increased notably with an increase in drying chamber pressure. A linear relationship between drying shrinkage ratio and dry basis moisture content was observed. The goodness of fit tests indicated that the proposed polynomial model gave the best fit to experimental results among the five tested drying models. The temperature dependence of the effective moisture diffusivity for the vacuum drying of the eggplant samples was satisfactorily described by an Arrhenius-type relationship.

Evaluation of global luminous efficacy models for Florianópolis, Brazil

Several global luminous efficacy models have been tested with daylight-measured data obtained for Florianópolis, Southern Brazil. The models have been used with their original coefficients, given by the authors and also with local coefficients obtained when the models were optimized with the data measured in Florianópolis. The evaluation of the different models has been carried out considering three sky categories, according to a higher or lower presence of clouds. For clear sky, the models tested have been compared with a proposed polynomial model on the solar altitude, obtained by the best fit of experimental points for Florianópolis. It has been proved that the model coefficients have a local character. If those models are used with local coefficients, there is no model that works better than the others for all sky types, but that for each sky category a different model could be recommended.